MIT Bates Linear Accelerator Center

1. Introduction to Optical Stochastic Cooling and the Bates Linear Accelerator Center at MITRobert P. RedwineDirector, Bates Linear Accelerator Center Muon Collider Design Workshop, BNL

2. MIT Bates Linear Accelerator Center Muon Collider Design Workshop, BNL

3. History • 500 MeV linear electron accelerator with recirculator, polarized electron source and storage ring • Recirculator nearly doubles energy to 1 GeV • Storage ring can stack pulses from the accelerator to at least 225 mA; beam stores for 25-30 minutes • Beam polarization is kept longitudinal at target with a Siberian Snake • Ran nuclear physics experiments for 31 years, under a cooperative agreement with US DOE Siberian Snake Muon Collider Design Workshop, BNL

4. Present • MIT now owns the site and facilities • Bates is a multi-purpose laboratory • 20+ physicists, engineers and technicians on-site Muon Collider Design Workshop, BNL

5. Optical Stochastic Cooling • Optical Stochastic Cooling (OSC) is potentially important for several applications, including a muon collider. • The MIT/Bates lab represents an almost ideal opportunity for a demonstration of OSC. • NP and HEP at DOE are evaluating a proposal from Bates to test OSC. • Dennis Kovar would like to hear directly from the muon collider community about the importance of pursuing OSC. Muon Collider Design Workshop, BNL

6. Optical Stochastic Cooling of a 100 GeVMuon Beam(A. Zholents & M. Zolotorev) ChristophTschalär Bates Linear Accelerator Center Massachusetts Institute of Technology Muon Collider Design Workshop, BNL

7. Goal: • Cool a beam of 109muons at 100 GeV in ≤ 4ms (muon life-time = 2.2 ms) Transverse: Longitudinal: Total 6-dimensional emittance reduction = 4·1010 Muon Collider Design Workshop, BNL

8. Charged particle beam delayed by magnetic bypass N S N S N Light pulse delayed and amplified Particle receives longitudinal kick from own amplified light pulse in 2nd undulator Particle in first undulator emits coherent light pulse of length Nl OSC Cooling Section Muon Collider Design Workshop, BNL

9. OSC Formalism Phase shift Mean shift Mean cooling per transition: Ns = number of muons whose light signals overlap Muon Collider Design Workshop, BNL

10. Maximize αL,T • Optimize G: incoherent heating = ½ coherent cooling for • Optimize phase shift → Dual challenge: make Ns very small, G very large Muon Collider Design Workshop, BNL

11. Conceptual Solution (Zholents & Zolotorev) • Stretch incoming beam bunch from 0.2m to 100m length • Compress δav from 10-3 to 2·10-6 → reduces Ns to → Three C=1100m Muon Collider Design Workshop, BNL

12. Initial and Final Beam Parameters in the Cooling Ring initial final change 2·10-4 2.5·10-61/80 1·10-4 1.2·10-61/80 2·10-6 2·10-91/1000 8·10-11 1.8·10-211/4·1010 Muon Collider Design Workshop, BNL

13. Initial and Final Lattice Parameters for Optimal Cooling at 0.8 μm Optical Wavelength initial final change 100 ~1000 ~10 4·10-4 3.3·10-283 -0.1 -30 300 -0.025 -25 1000 Muon Collider Design Workshop, BNL

14. Technical ChallengesCooler Lattice • Very large dispersion • Very large and rapid change of cooling section time-of-flight parameters: → use 3 parallel cooler rings for initial, middle, and final cooling phase → reduce time-of-flight parameter changes to ~6 and dispersion change to ~2 in each ring • Cool both x and y dimension of the beam → attach bypass to cooler ring to rotate transverse beam plane by 900 periodically Muon Collider Design Workshop, BNL

15. Light Amplifier • Optimized gain factor at the beginning of the cooling cycle, decreasing exponentially to 2·10-11 at the end, requires an average amplifier output power of for each of the 10 cooling sections. → Use fast Optical Parametric Amplifier (OPA) developed by MIT group (F. Kärtner). Expected power levels of 1 kW reachable with intensive development in 5-10 years Muon Collider Design Workshop, BNL

16. Conclusion • OSC for muon beams of 109 particles is conceptually feasible • Requires development of cooler lattices with large dispersions and rapidly varying time-of-flight characteristics • Requires development of kW-level OPA in the 1μm wavelength region • Requires experimental test of OSC to prove feasibility and develop basic tools and diagnostics Muon Collider Design Workshop, BNL

17. Optical Stochastic Cooling for a 2 TeVx2TeV Muon Collider & OSC Experiment at the MIT-Bates South Hall Ring F. Wang MIT-Bates Linear Accelerator Center • Comparison of muon collider designs: “conventional” vs. “OSC” • OSC experiment at Bates: motivation, plan Muon Collider Design Workshop, BNL

18. Comparison of 2TeV x 2TeV muon collider design Muon Collider Design Workshop, BNL

19. Nominal time-averaged luminosity: Luminosity at beam-beam limit: Muon Collider Design Workshop, BNL

20. Neutrino Radiation Challenges Bruce J. King, BNL-67408, CAP-281-Muon-00C, April 2000. Muon Collider Design Workshop, BNL

21. Neutrino-induced radiation dose B.J. King, PAC 318, 1999 “Equilibrium approximation” for worst-case radiation calculations. Unit of dose equivalent: 1 Sievert [Sv] =1 J/kg= 100 rem The U.S. federal off site radiation limit: 1 mSv/year=100 mrem/year. 1% Dfed : 1 mrem/year Muon Collider Design Workshop, BNL

22. Comparison of 2TeV x 2TeV muon colliders (Continued) *B. J. King, PAC 99, p.318. ** No vertical wave field Muon Collider Design Workshop, BNL

23. Shielding the Muon Collider Interaction Region C.J. Johnstone and N.V.Mokhov, PAC 97, p.414 Muon Collider Design Workshop, BNL

24. OSC in Muon Collider scheme OSC Cd=1100m C=8088m Muon Collider Design Workshop, BNL

25. OSC scheme for each type of muon Three C=1100m Muon Collider Design Workshop, BNL

26. Summary of comparison • OSC feature: Cooling at ~100 GeV • Much smaller emittance: • each transverse plane: ~1/8000, longitudinal ~1/400 • ~4400 times fewer muons per beam, same luminosity • Advantages: • Dramatic reduction of off-site neutrino induced radiation hazard • 50 times less proton beam pulse intensity • Background improvement in the detector • Disadvantages: • Increases the complexity of muon collider facility Muon Collider Design Workshop, BNL

27. OSC experiment at Bates First Experimental Demonstration of Optical Stochastic Cooling with the MIT-Bates South Hall Ring W. Barletta, P. Demos, K. Dow, J. Hays-Wehle, E. Ihloff, J. Kelsey, B. McAllister, R. Milner, R. Redwine (P.I.), S. Steadman, C. Tschalär, E. Tsentalovich, and F. Wang Bates R&E/Accelerator Center and Laboratory for Nuclear Science, MIT F. Kärtner, J. Moses, and A. Siddiqui Research Laboratory of Electronics, MIT M. Babzien, M. Bai, M. Blaskiewicz, M. Brennan, W. Fischer, V. Litvinenko, T. Roser and V. Yakimenko Brookhaven National Laboratory S.Y. Lee Indiana University Cyclotron Facility W. Wan, A. Zholents and M. Zolotorev Lawrence Berkeley National Laboratory Muon Collider Design Workshop, BNL

28. Motivation of experiment • OSC has never been demonstrated in practice. • The cost and time required for testing OSC in high-energy hadron machine or muon collider will be significant. • Experiment with e-beams is quick and cost-effective. • Why with Bates South Hall Ring • Bates SHR ring energy range is appropriate, machine lattice is very flexible. • There is a long straight section available for OSC insertion. • Bates facility is available for dedicated OSC testing. • Bates experiment goals • Proof-of-principle • OSC concept study: cooling mechanism, OSC & ring lattice integration, fast cooling test • Address key technical issues: optical amplifier, magnet bypass, diagnostics & control Muon Collider Design Workshop, BNL

29. MIT-Bates South Hall Ring • Distinguish OSC from damping due to synchrotron radiation • Low energy electrons • Large dipole bend radius • Long straight sections desirable for OSC apparatus • South Hall Ring, e- storage ring • Full energy injection at 300 MeV • Dedicated use of South Hall Ring for first OSC demonstration • Design tolerances consistent with existing technology • Optimize for SHR environment OSC apparatus C = 190.2 m = 9.14 m Successful beam development Run in April-May 2007 Muon Collider Design Workshop, BNL

30. Bates Experiment Parameters Growth (damping) rates at equilibrium state: Muon Collider Design Workshop, BNL

31. OSC Insertion SHR Lattice for OSC Experiment Muon Collider Design Workshop, BNL

32. 50 ps, 1030 nm Laser 20 MHz, 20 W, 1 mJ 2 nJ 40 mW Undulator Radiation BaF2 wedges 1mm Beam radius: f = 12 cm w = 0.5 mm 2 mm PPLN n=2 0.2 pJ 4 µW f = 380 cm f = 380 cm 24cm 103cm 270cm 103cm 270cm Lenses and wedges, 1mm, n=1.5 Total optical delay is only 5.5 mm ~ 20 ps Bates OSC apparatus: Optical amplifier and layout F. Kärtner, A. Siddiqui PPLN: Periodically Poled Lithium Niobate Muon Collider Design Workshop, BNL

33. Bates OSC apparatus: Small-angle bypass Based on Optical Parametric Amplifier: total signal delay ~20ps only! Then we can choose small-angle chicane with path length increase of 20 ps ~ 6 mm. 4 parallel-edge benders and one (split) weak field lens. Choose =65 mrad, L=6mm. Tolerances to conserve coherence are much relaxed for small-angle bypass. Muon Collider Design Workshop, BNL

34. SHR OSC experiment numerical modeling: x and optical amplification Observation of beam transverse size changes during cooling process Optimal cooling achieved by adjusting optical amplification. Muon Collider Design Workshop, BNL

35. OSC Tuning Diagnostics J. Hays-Wehle, W. Franklin • Interference signal is maximal when light amplitudes same (low gain alignment). • E2 is maximal for f=0 (f=/2 for OSC) use in feedback system. • Need analysis and bench test of phase feedback during high gain operation. • Correlate with beam size measurements (sync. light monitors, streak camera). Muon Collider Design Workshop, BNL

36. How technologies to support OSC are developing • High power laser amplifiers – rapid progress with DOD and industrial funding, expect 10X increase in average power in ~5 years • Sub-femtosecond timing – critical to future light sources for ultra-fast science; sub-fs capability over km distance expected ≤ 5 years • Superconducting wigglers – critical to and under development for future light sources; HTS magnets could play an important role Muon Collider Design Workshop, BNL

37. Summary of OSC experiment at Bates • Cooling of high energy hadron or muon beams holds major promise for increasing collision luminosity of hadron-hadron /electron-ion colliders, and for the realization of a multi-TeVmuon collider. • OSC is a promising cooling technique which has never been demonstrated. • The proposed Bates experiment utilizes an existing and available accelerator complex. • The collaboration contains the necessary expertise to carry out the experiment and to subsequently deploy it at possible high energy colliders. • Technologies to support OSC for high energy colliders are developing. • DOE proposal is under review. Muon Collider Design Workshop, BNL

38. Additional slides Muon Collider Design Workshop, BNL

39. 1996 design Muon Collider Design Workshop, BNL

40. Muon Collider Design Workshop, BNL

41. http://cupp.oulu.fi/neutrino/ Centre for Underground Physics in Pyhäsalmi (Finland), CUPP project, University of Oulu Muon Collider Design Workshop, BNL